'Real Housewives' Big Poppa ARRESTED

11/8/2012 7:40 AM PST BY TMZ STAFF

Lee Najjar -- who was known on "Real Housewives" as Kim Zolciak's mysterious ex-sugar daddy "Big Poppa" -- was arrested in Atlanta this week ... TMZ has learned.

Najjar was taken into custody by the Fulton County Sheriff's Dept. on November 6 ... though it's unclear why he was arrested.

According to law enforcement, Najjar has since been released from custody.

Najjar has developed a reputation as a fame whore ... especially when it came to flaunting his wealth. Back in 2009, he showed off his ATL mansion on an episode of MTV's "Teen Cribs" ... and then funded Kim Z's ridiculous spending sprees back when he was nailing her.

9:42 AM PT -- We've learned ... Najjar had a bench warrant out for his arrest for failing to appear in court to face allegations he failed to maintain a storm water system at one of his properties.

Najjar has already been hit with a $75,000 fine for violating the ordinance and was supposed to appear in court on July 5 ... but apparently, he blew off his court date.